One-way network interface

Abstract

Two embodiments of a one-way network interface card are disclosed, a transmit-only version and a receive-only version. A network controller mounted on the circuit card is coupled to the host computer via a host computer interface. A first processor is coupled to a network interface of the network controller. A second processor has a separate network interface for communicating with a remote computer. A one-way link is coupled between the first processor and the second processor. For the transmit-only embodiment, the one-way link only allows information to be transferred from the first processor to the second processor, and thus information may only pass from the host computer to the remote computer. For the receive-only embodiment, the one-way link only allows information to be transferred from the second processor to the first processor, and thus information may only pass from the remote computer to the host computer.

What is claimed is: 
     
       1. A transmit-only network interface card for a host computer, comprising:
 a single printed circuit card configured to be mounted in the host computer; 
 an Ethernet controller mounted on the single printed circuit card and coupled to the host computer via a host computer interface, the Ethernet controller having a network interface; 
 a source processor mounted on the single printed circuit card, the source processor directly connected to the Ethernet controller network interface, the source processor configured to forward information received from the Ethernet controller network interface on a separate output; 
 a one-way data link mounted on the single printed circuit card, the one-way data link having an input directly connected to the separate output of the source processor and an output, the one-way data link configured to transfer data only from the input of the one-way data link to the output of the one-way data link and to prevent any signal from passing from the output of the one-way data link to the input of the one-way data link; and 
 a destination processor mounted on the single printed circuit card, the destination processor having an input directly connected to the output of the one-way data link and a network interface, the destination processor configured to forward information received on the input of the destination processor to a remote computer via the destination processor network interface. 
 
     
     
       2. The transmit-only network interface card of  claim 1 , further comprising an external power interface, wherein the destination processor is coupled to the external power interface to receive power such that the destination processor only receives power via the external power interface. 
     
     
       3. The transmit-only network interface card of  claim 1 , wherein the single printed circuit board has three separate contiguous areas, a first area containing the destination processor, a second area containing the Ethernet controller and the source processor and a third area disposed directly between the first area and the second area, the third area containing no electrical connections between the first area and the second area, the one-way data link spanning the third area with the input of the one-way data link within the second area and the output of the one-way data link within the first area. 
     
     
       4. A receive-only network interface card for a host computer, comprising:
 a single printed circuit card configured to be mounted in the host computer; 
 an Ethernet controller mounted on the single printed circuit card and coupled to the host computer via a host computer interface, the Ethernet controller having a network interface; 
 a destination processor mounted on the single printed circuit card, the destination processor having a separate input and an output directly connected to the Ethernet controller network interface, the destination processor configured to forward information received on the separate input to the Ethernet controller network interface via the destination processor output; 
 a one-way data link mounted on the single printed circuit card, the one-way data link having an input and an output directly connected to the separate input of the destination processor, the one-way data link configured to transfer data only from the input of the one-way data link to the output of the one-way data link and to prevent any signal from passing from the output of the one-way data link to the input of the one-way data link; and 
 a source processor mounted on the single printed circuit card, the source processor having a network interface and an output directly connected to the input of the one-way data link, the source processor configured to forward information received from a remote computer via the source processor network interface on the source processor output. 
 
     
     
       5. The receive-only network interface card of  claim 4 , further comprising an external power interface, wherein the source processor is coupled to the external power interface to receive power such that the source processor only receives power via the external power interface. 
     
     
       6. The receive-only network interface card of  claim 5 , wherein the single printed circuit board has three separate contiguous areas, a first area containing the source processor, a second area containing the Ethernet controller and the destination processor and a third area disposed directly between the first area and the second area, the third area containing no electrical connections between the first area and the second area, the one-way data link spanning the third area with the input of the one-way data link within the first area and the output of the one-way data link within the second area.